Planar SOA Waveguide With Taper Coupling for Low-Heat Operation

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Solution Overview

Problem

State-of-the-art semiconductor optical devices face mechanical fragility issues due to ridge structures, leading to heat dissipation that affects quantum efficiency, and existing solutions exacerbate these problems.

Innovation Solution

A semiconductor optical device with a U-shaped central longitudinal cavity and varying width and height, featuring a first active zone and a taper zone, along with specific layer configurations and coatings, enhances mechanical strength and optical mode coupling while minimizing heat dissipation and parasitic effects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If ridge structures are used to provide mechanical support, then mechanical strength is improved, but heat dissipation increases which disturbs quantum efficiency

Engineering Contradiction:
Improvemechanical strengthVSAvoidheat dissipation
Core Design Contradiction:
StrengthVSLoss of energy

Solution Approach 1:

The patent removes the ridge structure from the device architecture and replaces it with a planar waveguide configuration. This extraction of the problematic ridge element eliminates the source of heat dissipation while maintaining mechanical support through the substrate and cladding layers, thereby resolving the contradiction between mechanical strength and heat dissipation.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent employs composite material structures with different thermal and mechanical properties. The device uses a combination of semiconductor layers with optimized thermal conductivity arranged in a planar configuration, allowing heat to be efficiently conducted away from the active region while maintaining structural integrity without requiring ridge structures.

Inventive Principle:
Principle #40Composite materials

2Strength

If classical techniques are used to compensate mechanical fragility, then mechanical strength is improved, but heat dissipation increases

Engineering Contradiction:
Improvemechanical strengthVSAvoidheat dissipation
Core Design Contradiction:
StrengthVSTemperature

Solution Approach 1:

The patent replaces the mechanical ridge structure with an optical waveguide configuration that relies on refractive index differences rather than mechanical support. This substitution eliminates the need for classical mechanical reinforcement techniques that generate heat, achieving both mechanical stability and thermal management through optical confinement.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Ease of operation

If taper zone is introduced for optical coupling, then coupling with optical fiber is improved, but device complexity increases

Engineering Contradiction:
Improveoptical couplingVSAvoiddevice complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent achieves optical coupling by transitioning from a confined waveguide mode to a free-space optical mode through a gradual expansion in the transverse dimension. This dimensional transition creates a taper zone that adiabatically transforms the optical mode, enabling efficient coupling with optical fibers while maintaining a relatively simple planar device architecture.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The device maintains single optical mode performance, facilitates easy coupling with optical fibers, and reduces mechanical weakness, heat accumulation, and parasitic capacitance, improving high-speed data transmission.

Implementation Method 1

a layer of n-inactive III-V optical waveguide material positioned on the layer of n-doped III-V semi-conductor material inside said cavity, said layer of n-inactive III-V optical waveguide material having an inverted T shape in a cross-section perpendicular to the longitudinal axis XX'

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

a layer of p-doped III-V semi-conductor, a central ribbon having a width β and comprising, on the edge of the slab, a first buried optical waveguide beneath a layer of p-doped III-V semi-conductor

Methodology Applied
Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 3

a first active zone, wherein the bottom surface and the upper surface of the base are parallel to each other and spaced from each other by a constant height δ = δ1

Methodology Applied
Scientific EffectStimulated emission:

Data Source

PatentEP4311042B1Opto-electronic device
Publication Date: 2025.10.15 NOKIA SOLUTIONS & NETWORKS OY
  • EP4311042B1 patent drawingFigure 1A~1B
  • EP4311042B1 patent drawingFigure 2A~2B
  • EP4311042B1 patent drawingFigure 3A~4

AI summary

The present invention concerns an optoelectronic device D such as a Semiconductor optical amplifier (SOA) working in a continuous wave condition and able to amplify high frequencies optical signals. The optoelectronic device D comprise an active zone I (such as SOA) with a slab (3) in a direct bias working in a continuous wave and a taper zone(II) connected to the active zone (I).